Week 2 blog.
I am finding it quite a challenge to learn things completely unrelated to my previous skill base. I have to read things several times to understand and be able to recall information. This week has been busy and unpredictable meaning that I am trying to catch up on my learning in one day. The three hours a week guide is way out for me. I don’t know if it is for other people.
So to volcanoes and climate change.
Solar radiation and volcanoes are two major influences on the climate. There are clear links between major volcanic eruptions and periods of cooler global temperatures. Volcanoes throw gasses, debris such as ash and particles called aerosols high into the atmosphere. They then are circulated around the globe by air movement. Aerosols can vary in size and can be made of a variety of substances. They can also combine to make hybrid compounds that are hard to identify. Some aerosols can seed clouds by attracting water vapour into raindrops, others make the water vapour stay too small to form clouds and so prevent rain. Some aerosols can cool the earth by reflecting light/heat out into space, other types absorb heat and then reflect it down to earth. 90% of aerosols have natural origins, 10% is created by man through things like cars, slash and burning forests, industrial processes etc.
The key scientific principles are as follows. Heat radiation from the sun reaches the earth as well as other planets in the solar system. Unlike Mars and Venus, our closest planetary neighbours, the earth has an atmosphere which allows the heat to pass through and also keep some of the heat from escaping as it bounces back off the earths surface. Without this blanket effect the earth would have an average temperature of -30C rather than the current average of 15C. Blanket rather than greenhouse effect is a better analogy for this activity. Greenhouses keep warmer by preventing conductive loss (windchill). Blankets insulate.
As the heat reaches the earth’s surface a proportion is absorbed and the remainder reflected. The type of surface (sea, rock, ice) affects the amount that is reflected. This is called the albedo effect and is a feedback system. Ice reflects the most, oceans absorb the heat, warm up and melt the ice.
The earth has a number of complex feedback mechanisms which regulate the overall climate. They are called positive or negative but this is not an indicator of their being good or bad for the overall climate. The water cycle is the most significant positive ( in that it heats) feedback cycle. Water is drawn up into the atmosphere through evaporation and transpiration, it then falls as precipitation ( rain, snow). Water in the atmosphere absorbs heat as it bounces back form the earths surface and bounces a portion of it back to earth, this increases the heat at the earths surface and creates more evaporation and is repeated in a spiralling effect.
A negative feedback system is created when carbon dioxide in the atmosphere is limited by being stored on the ocean floor after combining with silicates in rocks as they are eroded. This removes CO2 in the atmosphere.
Ozone is a greenhouse gas in the lower portion of the atmosphere. In the stratosphere is has an important non greenhouse function of blocking ultraviolet rays.
This reflection is difficult but in fact makes me learn at a deeper level. I am unable at the moment to conceptualise the whole climate system.
I have enjoyed week one, but i have been surprisingly anxious. The prospect of a test certainly focussed my mind. I think I was concerned that this is outside my own area of expertise and so i don’t have easy places to peg and sort the information or knowledge to build upon. I was disappointed that some of the participants felt that it was too simple. I didn’t.
The style and content is excellent, the length of the videos is just about right. They are thought provoking and not too long to fit into a busy day. I find that I am watching, thinking and then going back and watching again.
I have learned about the complexity of the water cycle, didn’t know that there were names for the different spheres, or indeed so many spheres. Are water plants and animals a part of the bio sphere or a part of hydrosphere?
Why does the media not talk about the albedo effect, it seems crucial to me. I had previously thought that the problem was rising sea levels not a loss of a key reflection of energy.
I bombed out on the first two questions in the test. I even went back and listened to the videos. If we get it wrong three times perhaps you could tell us the right answer, or why our answers were wrong?